Synthesis of halogenated naphthoquinones

ABSTRACT

This invention relates to a method of preparing halogenated naphthoquinones by hydrolyzing hexahalogenated dihydronaphthalene in an acid medium, at an elevated temperature and in the presence of available halogen.

Ere mi 1 [111 3,7293% Fuhflhage Ar. 17, 1973 [541 SYNTHESIS er HALOGENATED [56] References Cited NAPHTHOQUINONES UNITED STATES PATENTS Inventor: Donald Fuhlhage, Kansas City, 2,414,008 1/1947 Alquist et a1 ..260/396R MO. 3,433,812 3/1969 Buzbee et a]. ..260/396 R [73] Assignee: Thompson-Hayward Chemical Co., Primary Examiner vivian Gamer Kansas City Attorney-Russell G. Pelton and William H. Saltzman [22] Fried: I June 5, 1969 ABSTRACT PP N05 330,387 This invention relates to a method of preparing halogenated naphthoquinones by. hydrolyzing hex- [52] Us. CLm260/396 R 204/158 HA, 204/163 HE ahalogenated dlhydronaphthalene n an acid medlum, at an elevated temperature and 1n the presence of [51 1 int. available halogen. [58] Field of Search ..260/396 R 4 Claims, N0 Drawings dichloro-l,4-naphoquinone is known to possess fungicidal properties and may be employed for such purposes in any manner generally recognized by the skilled ,worker to achieve such objectives.

The process of the instant invention comprises a number 'of steps beginning with hexahalogenated dihydronaphthalene, for example, hexachlorodihydronaphthalene such as 1,1,2,3,4,4-hexahalo-2,3- dihydro-naphthalene as the starting material. The hexahalogenated dihydronaphthalene starting material of the instantinvention may be prepared in any manner known to the art, however in the practice of this invention it has been found most satisfactory to prepare the hexahalonaphthalene starting material by halogenation of naphthalene in the presence of a light catalyst.

In general, the hexahalogenated dihydronaphthalene starting material is subjected to hydrolysis in an acidic medium and at an elevated temperature to yield the 2 halo-1,4-naphthoquinone intermediate of this invention. The 2-halo-l ,4-naphthoquinone intermediate may be. directly converted -without isolation to the dihalogenated naphthoquinone final product by halogenation thereof.

More particularly, the hexahalogenated- I dihydronaphthalene is hydrolyzed in an acidic medium,

for example, a medium comprised of about 5 to 30 percent water and 70 to 95 percent acid, wherein the acid may be either an organic acid, such as acetic or propionic acid, or a mineral acid, such as sulfuric acid, or a combination of both. The hydrolysis reaction is carried out at an elevated temperature of above about 75 C., and preferably at a temperature of from about 90 to 120 C, and may be otherwise carried out in any manner known in the art. The resultant product of the hydrolysis reaction, a monohalonaphthoquinones intermediate, may be further directly treated without separation or purification from the'hydrolysis reaction medium, by subjecting said intermediate containing medium to halogenation with a halogenating agent, for example, halogen gas, acyl halides, and other such agents known to provide a source of available halogen in' such reactions, to yield the desired dihalogenated naphthoquinones final products These final products may then be further treated, as by generally known precipitation and recrystallization procedures to yield the purified dihalogenated naphthoquinone final products.

The invention is illustra ted by the following examples:

EXAMPLE 1 To a solution of 64 g. of naphthalene-in 185 ml of carbon tetrachloride, illuminated by a Sylvania sunlamp 275W), was added 142 grams of chlorine over a period of 4% hours. The reaction temperature was held between 55 60 C. After removal of carbon tetrachloride, infrared analysis showed the crude product to contain 63 percent of l,l,2,3,4,4 hexachloro-2,B-dihydronaphthalene by weight.

EXAMPLE 2 To a solution of 135 g. of mixed isomers of l,2,3,4,- tetrachloro-l,2,3,4-tetrahydro-naphthalene in 185 ml. of carbon tetrachloride, illuminated by a Sylvania sun- ]amp (275W) was added 71 grams of gaseous chlorine over a period of 4 hours. The reaction temperature was held between 55 60 C. The crude product was found to contain 110 grams of l,1,2,3,4,4 hexachloro-2,3- dihydronaphthalene.

EXAMPLE 3 To a solution of 100 ml. of propionic acid, 25 ml. of sulfuric acid, and 30 ml. of water was added with stirring, grams of crude l,l,2,3,4,4-hexachloro-2,3- dihydronaphthalene prepared in accordance with the procedure set forth in Example 1. The resulting mixture was then stirred for 4 hours at a temperature of 95 100 C, while chlorine gas was bubbled through the stirred mixture at such a rate that a slight excess of chlorine was always present. The resultant mixture was found to contain 18.6 grams of 2,3-dichlor0-l,4- naphthoquinone. Cooling the reaction mixture gave 17.8 grams of a yellow precipitate containing 90 percent 2,3-dichloro-l ,4-naphthoquinone.

EXAMPLE 4 A solution of 5.0 grams of crude 1,l,2,3,4,4-hexachloro-2,3-dihydronaphthalene in 30 ml. of carbon tetrachloride was added dropwise with stirring to a mixture of 100 ml. of acetic acid, 20 ml. of water, and 5 ml. of sulfuric acid at a temperature of 100 C. The carbon tetrachloride was allowed to escape through an air condenser. After the addition was complete (one-half hour) the temperature was held at 100 C. for 5 hours. Infrared analysis of the reaction mixture showed a 28 I percent yield of 2-chlorol ,4-naphth'oquinone.

EXAMPLE 5 achloro-2,il-dihydronaphthalene, there is obtained 2- bromol ,4-naphthoquinone.

The invention may be embodied within the scope of the appended claims.

What is claimed is:

1. A method for the preparation of a 2,3-dihalogenated naphthoquinone which comprises hydrolyzing al, l, 2, 3, 4, 4-hex'ahalogenated 2, 3- dihydronaphthalene, wherein the halogen is bromine or catalyst.

3. The method of claim 1 wherein the hexahalogenated dihydronaphthalene is prepared by treatment of naphthalene with a halogen in the presence of a light catalyst.

4. The method of claim 1 wherein the hydrolysis is carried out at a temperature of between about to C. 

2. The method of claim 1 wherein the hexahalogenated dihydronaphthalene is prepared by halogenating a tetrahalo-tetrahydronaphthalene by treatment with a halogen in the presence of a light catalyst.
 3. The method of claim 1 wherein the hexahalogenated dihydronaphthalene is prepared by treatment of naphthalene with a halogen in the presence of a light catalyst.
 4. The method of claim 1 wherein the hydrolysis is carried out at a temperature of between about 90* to 120* C. 